CN102858529A

CN102858529A - Composite foam product

Info

Publication number: CN102858529A
Application number: CN2011800201467A
Authority: CN
Inventors: M·马克
Original assignee: Vertex LLC
Current assignee: Vertex LLC
Priority date: 2010-02-22
Filing date: 2011-01-31
Publication date: 2013-01-02
Anticipated expiration: 2031-01-31
Also published as: US8715437B2; EP2539144A1; US20110206926A1; EP2539144A4; WO2011102954A1; CN102858529B; HK1179924A1

Abstract

A composite foam product comprising a foam core surrounded by a gas- impermeable film. The gas-impermeable film retains the gas formed from the blowing agent so that the pressure inside the foam core is above ambient pressures.

Description

The composite foam product

The cross reference of related application

The sequence number that the application submitted to based on February 22nd, 2010 is U.S.'s non-provisional application of 12/710,098 and has required its priority that this non-provisional application is hereby incorporated by.

Invention field

The present invention generally relates to the method for composite foam product and the described composite foam product of preparation.

The description of association area

Aspect robustness, foam is from the rigid material that is suitable for Application in Building to the flexible material that is used for cushion and packaging material.Aspect abscess formation, the scope of these foams contains the abscess foam of perforate or intercommunication to closed pore or single hole foam.Foam structure can be from greatly to carefully.Electricity, heat, mechanics and chemical property can change in wide scope, and this depends on thermoplastic resin composition and the method for selecting to produce foam.

Froth pulp can be by the method preparation of broad variety.In certain methods, during processing with gaseous state " blowing agent " but add expanded material.But additive method relates to and prepare gaseous foaming agent during processing in expanded material.Blowing agent usually has the foam structure that is far smaller than by the density of the resin of its preparation foam and works by thermoplastic resin being expanded make.Bubble forms and by heat or decompression or expand by the chemical reaction process that wherein relates to gas on every side at " nucleating point ".Additive can be introduced resin promoting specific blowing agent nucleation, and therefore obtain more uniform distribution of cells.

Gas from the blowing agent that is used to form the foam bubble pore structure can be stayed under supercharging in the abscess of most of closed-cell foams at first.Yet when foam was exposed in the environment, gaseous foaming agent oozed out the simultaneously component gas infiltration foam bubble pore structure of surrounding air from the foam bubble pore structure.That is, nitrogen and oxygen flow into foam from ambient air, and also have blowing agent to flow out from foam.Inflow/discharge rate depends on parameter and changes, and described parameter is the molecular dimension of gaseous foaming agent and polarity, the polymer type of formation foam, abscess-size, foam structure, pressure and temperature for example, and environmental condition.But final result is that the final and environmental pressure of the pressure of gas interior in the foam abscess reaches balance.This for even closed-cell foam just so because gas molecule can permeate and move through the polymer molecule that consists of foam.

The invention summary

The present invention relates to comprise the improved composite foam product of the foam core with a plurality of abscesses.Hermetically sealable film surrounds the outer surface of foam core fully and adheres to outer surface.During foaming process or at once afterwards, hermetically sealable film puts on the outer surface of foam core, so that foaming agent gas is retained in hermetically sealable film and a plurality of abscess.Therefore pressure in the composite foam product surpass environmental pressure.Do not need pump, valve or other equipment that the pressure of the rising of hope is provided in the composite foam product.

On the other hand, the present invention relates to the composite foam product of " substantially by being formed by airtight membrane-enclosed foam core ".Therefore, the present invention is comprised of following substantially: have a plurality of foam core that are the abscess of hole-closing structure, and tight adhesion is in the whole outer surface of foam core so that foaming agent gas is retained in the hermetically sealable film in the hermetically sealable film.Pressure in a plurality of abscesses remains under the pressure above environmental pressure.Other components may reside in the foam core, for example elastomeric component, crosslinking agent, heat stabilizer, light stabilizer, filler, nucleator, antioxidant, colouring agent and pigment.Yet these components must not remain on the pressure in the foam core on the environmental pressure, because hermetically sealable film provides this function.In addition, term " substantially by ... form " get rid of the additive method of pressurized foaming core, for example pump, valve or other plant equipment.

Still on the other hand, the present invention relates to form the method for composite foam product as herein described.Generally speaking, but described method comprises the step that is formed foam core by expanded material and blowing agent.Have a plurality of abscesses in the foam core, the gas of self foaming agent is retained in wherein so that a plurality of abscess is being higher than under the pressure of environmental pressure in the future.Described method also comprises the step that hermetically sealable film is adhered to the foam core outer surface.Adhering step with form that step is carried out simultaneously or after forming step, at once carry out, with under being higher than the pressure of environmental pressure future self foaming agent gas be retained in the abscess.Can choose wantonly and use adhesive to adhere to better foam core and hermetically sealable film.

In one aspect, but foam core by will expanded material and described blowing agent insertion mould, but and then cross over mould and apply alternation radio frequency dielectric field and prepare to heat described expanded material.For example, foam core can be by using the alternation radio frequency dielectric field preparation that produces between the first top electrodes and the second bottom electrode.In one aspect, hermetically sealable film is after-applied in the formation foam core.In yet another aspect, form foam core and the step that hermetically sealable film adheres to the foam core outer surface almost carried out simultaneously.Therefore in one aspect, said method comprising the steps of: but expanded material and blowing agent are inserted mould, surround expandable mixtures and blowing agent with hermetically sealable film, but and cross over mould and apply alternation radio frequency dielectric field with the heating expanded material and form foam core.The calibration of alternation radio frequency dielectric field is about 1MHz to 100MHz, and the voltage of alternation radio frequency dielectric field preferably is about 1000-10,000V.

In one aspect, said method comprising the steps of: hermetically sealable film is arranged on the bottom die of die cavity of the mobile mold apparatus with mold and bottom die; Foaming mixture is placed on the hermetically sealable film in the die cavity; Other hermetically sealable film is placed on the foaming mixture in the die cavity, so that hermetically sealable film surrounds foaming mixture; Form described foam core with the described foaming mixture of heating.Described mobile mold apparatus can have movably barrier film, and described barrier film separate foaming mixture and described hermetically sealable film with the replaceable liquid that can pass through to move one or more gateways (port).Heating expands foaming mixture and therefore so that removable barrier film moves and by described one or more gateways replacement fluid.

Attached advantage and the new feature of other aspects of the present invention and the present invention will partly be set forth in the specification of back, and partly will become for those skilled in the art obvious during content below check, perhaps can learn from the practice of the present invention.Objects and advantages of the present invention can be by means and combination realization and the acquisition that particularly points out in appended claims.

The accompanying drawing summary

Figure 1A is the cross section of composite foam product of the present invention, and it has illustrated by airtight membrane-enclosed foam core.Show the composite foam product behind the too much hermetically sealable film of cross cutting.

Figure 1B is the cross section of composite foam product of the present invention, and it has illustrated by airtight membrane-enclosed foam core.Show the composite foam product before the too much hermetically sealable film of cross cutting.

Fig. 2 is the cross-sectional view that at once hermetically sealable film is adhered to the equipment that exemplifies of foam core after forming foam core.

Fig. 3 A and Fig. 3 B are used for the on-the-spot cross-sectional view that hermetically sealable film is adhered to the mobile mold apparatus that exemplifies of foam core during foam core forms.Fig. 3 A has illustrated the hermetically sealable film that surrounds foaming mixture before applying any thermosetting foam core.Fig. 3 B has illustrated in the formation of the foam core of hot adhesion hermetically sealable film on it after the heating.

Fig. 4 A and 4B have illustrated the mat that comprises composite foam product of the present invention.Fig. 4 B is the cross section that takes off by the line 4b shown in Fig. 4 A.

The detailed description of preferred embodiment

Turn to now Figure 1A, the present invention relates to improved composite foam product 20, it comprises the foam core 24 with a plurality of abscesses.The outer surface of foam core 24 is surrounded by hermetically sealable film 22.During foaming process or at once afterwards, apply hermetically sealable film, so that foaming agent gas is retained in hermetically sealable film and a plurality of abscess.Because foaming agent gas can not be overflowed by hermetically sealable film, so the pressure in the foam core of joint product surpasses environmental pressure.Generally speaking, the pressure in the composite foam product is about 1.1,1.2,1.3,1.4,1.5,1.6,1.7,1.8,1.9 or 2.0 times of environmental pressure (or between some scopes).Therefore, in one aspect, the pressure in the foam core is about 1.1,1.2,1.3,1.4,1.5,1.6,1.7,1.8,1.9 or 2.0atm.Generally speaking, pressure is about 1.2-1.5atm, but interior pressure will depend on the density of foam core and change.In addition, keep for a long time the pressure that raises, usually some months and even several years.Do not need pump, valve or other equipment that the rising pressure of hope is provided in the composite foam product.

Composite foam product 20 is compared with the foam core that does not have hermetically sealable film and is shown improved rebound performance.In one aspect, measure by ASTM D7121-05, the resilience of composite foam product than the corresponding foam product height that does not have hermetically sealable film at least about 10%.On the other hand, the resilience of composite foam product is than the corresponding conventional foam product that does not have hermetically sealable film high about 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50% (or between some scopes).

Joint product 20 is compared with the foam core that does not have hermetically sealable film and is shown improved compression set properties.In one aspect, the compression set of composite foam product is lower at least about 50% than the corresponding foam product that does not have hermetically sealable film.On the other hand, the compression set of composite foam product is than corresponding conventional foam product low about 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10% or 5% (or between some scopes).

The physical property of understanding hermetically sealable film can be changed the physical property of composite foam product.For example, owing to around foam core, have hermetically sealable film, so hot strength, wearing and tearing and tearing strength will all be affected.

The invention still further relates to the method for preparing the composite foam product.Generally speaking, during foaming process or afterwards the scene applies hermetically sealable film at once, so that foaming agent gas is retained in hermetically sealable film and a plurality of abscess.Generally speaking, in case use routine techniques to prepare foam core, then at about 120 minutes, preferably at 60 minutes, and more preferably in 30 minutes, apply hermetically sealable film.Preferably the delay of the formation from the formation of foam to the hermetically sealable film is short as far as possible.Therefore on the other hand, after forming foam core, apply hermetically sealable film in 1,2,3,4 or 5 minute.Will be appreciated that forming and apply hermetically sealable film in foam core can depend on many factors with the time delay (if any) between the internal object pressure of realizing wishing in foam core, the pressure of abscess, the temperature of foam abscess during for example the polymer type of the molecular dimension of gaseous foaming agent and/or polarity, formation foam, foam bubble hole dimension, foam bubble pore structure, foam core form, and environmental condition.

Foam core 24 can be made by any suitable foaming mixture well known by persons skilled in the art.But foaming mixture preferably comprises one or more expanded materials and one or more blowing agents.

But expanded material always comprises known thermoplasticity or thermosets, and their mixture.Example comprises polyvinyl resin, acrylic resin and other thermoplastic resins.The example of suitable polyvinyl resin is high density polyethylene (HDPE), low density polyethylene (LDPE) (" LDPE "), linear low density of polyethylene, ethane-acetic acid ethyenyl ester (" EVA ") copolymer, ethylene-methacrylic acid copolymer, ethylene-acrylate-maleic anhydride terpolymer, the ethylene-methyl methacrylate glycidyl ester copolymer, ethylene-methyl methacrylate ethylene oxidic ester-methacrylate terpolymer, ethylene-methyl methacrylate ethylene oxidic ester-vinyl acetate terpolymers, ethylene-alpha-olefin copolymer, the polyolefin of modification, haloflex, and other thermoplastic synthetic resins that mainly formed by ethene.The example of suitable acrylic resin is Noblen, propylene-ethylene random copolymer, propylene-ethylene block copolymer, propene-1-butene random copolymer, propylene-ethylene-butene terpolymer etc.The example of suitable thermoplastic synthetic resin is polyvinyl chloride (" PVC "), polyvinyl chloride-acetate copolymer, chliorinated polyvinyl chloride, polyvinyl chloride-vinyl-vinyl acetate copolymer, polyvinyl chloride-urethane copolymers, acrylonitrile-butadiene-styrene copolymer, MBS, SBS, acrylonitritrile-styrene resin, and other vinyl-based toners.But preferred expanded material comprises PE-EVA foam, PVC foam, vinyl nitrile foam, PVC-nitrile rubber foam and neoprene foams.Certainly, but also can use other expanded materials well known by persons skilled in the art according to the present invention.In addition, expection the present invention foaming technique and expanded material that will can be used for recently developing.

Blowing agent comprises the Compressed Gas that expands, leaves the soluble solids of abscess when leaching, show the liquid of abscess when they becomes gas when earth pressure release, and decomposes under heat affecting or reaction forms the solid chemicals of gas.Any suitable blowing agent can be used in the expandable mixtures.The blowing agent that exemplifies comprises halohydrocarbon for example fluorocarbon and CFC; Hydrohalogenation carbon is HFC and hydrochlorofluorocarazeotropic for example; Alkyl halide, for example chloromethane and chloroethanes; And hydrocarbon.The fluorocarbon blowing agent that exemplifies comprises 1,1-Difluoroethane (HFC-152a); 1,2-Difluoroethane (HFC-152); HFA 134a (HFC-134a); 1,1,2,2-HFC-134a (HFC-134); 1,1,1-HFC-143a (HFC-143a) and 1,1,2-HFC-143a (HFC-143); Pentafluoroethane (HFC-125).The hydrocarbon that exemplifies comprises alkane or the olefine with 1-9 carbon atom.The alkane that exemplifies comprises propane, normal butane, iso-butane, pentane, isopentane, hexane, isohexane, heptane etc.Other suitable blowing agents also comprise CBA for example N-nitroso compound, sulfohydrazide, sulfonyl semicarbazides, ammonium and azo compound.These compounds comprise dinitrosopentamethylene tetramine, N; N'-dinitroso-N-N'-dimethyl terephthaldehyde acid imide, 4; 4'-oxygen connection two (benzene sulfonyl hydrazide), ptoluene-sulfonyl semicarbazides, p, p'-oxygen connection two (benzenesulfonyl semicarbazides), azo-2-carboxylic acid's barium salt, diisopropyl azo-2-carboxylic acid, ammonium carbonate, carbonic hydroammonium, saleratus, two azoaminobenzenes, two azo amino toluenes, azodicarboamide, two azo isobutyronitriles etc.Aspect preferred, blowing agent comprises one or more blowing agents pure or inertia, for example air, carbon dioxide, nitrogen, argon gas, xenon, Krypton, helium, water, and form the reagent of these compounds.Nitrogen and carbon dioxide have especially cheapness, obtain and nonflammable advantage easily, and are not counted as the ozone layer of the earth harmful.Preferred CBA normally decomposes under specified temp and discharges for example low molecular weight organic compound of nitrogen, carbon dioxide or carbon monoxide of inert gas.A kind of preferred inertia blowing agent is azodicarboamide AZ130.In one aspect, the gaseous composition by the blowing agent preparation is 42%N ₂, 21%CO ₂, 21%NH ₃And 16%CO.

Also will understand two or more the mixture that blowing agent can comprise any above-mentioned blowing agent.Referring to such as Lee etc., U.S. Patent No. 6,583,190; Lee etc., U.S. Patent No. 5,348,984; Lee etc., U.S. Patent No. 5,462,974; And Ealding, U.S. Patent No. 3,939,238.When using multiple blowing agent, blowing agent can decompose and discharge foaming agent gas under identical or different temperature.

It is about 30 that the amount of introducing the blowing agent of foaming mixture is about 0.2-, and preferably about 0.5-is about 10, and 1.5-8 part/hundred part resin (" phr ") most preferably from about.Therefore in one aspect, blowing agent can account for 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29 or 30phr of foaming mixture, perhaps therebetween some scopes.The amount of the blowing agent that uses will depend on the composition of expanded material and the density of foam core.For example, for the EVA/LDPE foam core with about 2lbs/ft3 density, usually use the 18phr azodicarboamide.Has 1.5lbs/ft ³The EVA/LDPE foam core of density is used about 25phr azodicarboamide usually.

If wish that foaming mixture can randomly comprise elastomeric component for example polyisobutene, polybutadiene, ethylene/propene copolymer, and ethylene/propene alkadienes interpretation.Other possible other components comprise one or more crosslinking agents, heat stabilizer, light stabilizer, filler, nucleator, antioxidant, colouring agent and pigment, and lubricant.For example, crosslinking agent comprises peroxide, for example cumyl peroxide, dibenzoyl peroxide, t-butyl perbenzoate, 2, two (t-butyl peroxy)-2 of 5-, 5-dimethylhexane and 2,5-dimethyl-2,5-two (t-butyl peroxy).Operable inertia nucleator comprises magnesia, calcium oxide, zinc oxide, lead oxide, barium monoxide and talcum.

The proper lubrication agent comprises such as, but not limited to various hydrocarbon, such as paraffin; Paraffin oil; Low molecular weight polyethylene; Oxidic polyethylene; Amide waxe; Fatty acid metal salts; Fatty acid ester is butyl stearate for example; Fatty alcohol, for example cetanol, stearyl alcohol or octadecanol; Metallic soap is calcium or the zinc salt of oleic acid for example; Organic acid fat acid amides; Polyol esters is glycerin monostearate, distearyl acid six glyceride and their mixture for example.The example of the possible aliphatic acid that uses is included but not limited to stearic acid and calcium stearate.

In addition, will understand by silk thread or fiber or fabric are included in wherein, can the reinforced foam core.Typical reinforce can be for example fibrous glass or carbon fiber of inorganic material; Natural organic fiber such as silk, cotton, wool etc., perhaps synthetic organic fibre such as carbamate fibre, nylon yarn, RIPSTOP, aromatic polyamides silk thread and fabric etc.This reinforce can be laminated in the foam core (on hermetically sealable film or below), perhaps introduces foaming mixture.

Foam core preferably has hole-closing structure.Generally speaking, closed-cell foam does not have the hole that communicates/mouth.The typical density of foam core is about 25 pounds/cubic feet of about 0.5-.Preferred foam density is about 2-12 pound/cubic feet.Generally speaking, the density of foam core is about 2,3,4,5,6,7,8,9,10,11 or 12 pounds/cubic feet, or some scopes therebetween.

In the present invention, do not see through the outer surface that film surrounds foam core.In one aspect, hermetically sealable film comprises the material that is selected from polyolefin, polyurethane, polyvinyl compound, polyethers and polyester.The hermetically sealable film that exemplifies comprises by following those that make: polymethylpentene homopolymers or copolymer, Natene or copolymer, polypropylene homopolymer or copolymer, polyethers-block-amide copolymer, polyether-polyester copolymer, copolyesters and polyvinyl chloride.On the other hand, hermetically sealable film comprises polyethylene/vinyl alcohol copolymer (" EVOH "), SARAN, poly-(vinylidene chloride) copolymer (" PVDC "), PETG (" PET "), polyamide (" PA "), nylon or thermoplastic polyurethane (" TPU ").Hermetically sealable film can comprise one or more material layers.In addition, these layers can different directions apply.

Hermetically sealable film can have any suitable thickness.Generally speaking, described film is about the 1-200 mil thick, the preferred thickness of about 2-100 mil, and realize good result with the thickness of about 50 mils of about 10-.Generally speaking, use the film of the thickness with about 10,20,30,40,50,60,70,80,90 or 100 mils or some scopes therebetween.Thickness can be even or non--uniformly.

In the present invention, with foam core on basic all its outer surfaces close attachment (gluing, bonding, welding etc.) in the inner surface of hermetically sealable film.That is, foam core with respect to wall pressure tight and wall clamp-on with respect to core.Do not have gas between hermetically sealable film and foam core, this will cause these regional undesirable inflations.Foam core contact with tight adhesion between the outer wall produce can not expected degree product integrality and can not be expectedly good impact absorption ability.

Can randomly use one or more adhesives hermetically sealable film to be adhered to the outer surface of foam core.This adhesive is activated adhesive the most expediently, and for example photoactivation adhesive, UV activated adhesive or heat-activatable adhesive are to allow foam core to adhere to together on the hermetically sealable film and bonding at once after foam core forms then.Typical heat-activatable adhesive is the Royal adhesive DC511324 material of being sold by Uniroyal.This adhesive is poly-(the carbamate)/isocyanate adhesives of two parts, and it has additional advantages, is water base.The thermal activation under 300-325F of this material forms tough and tensile adhesion bonding.Other useful adhesives can comprise epoxy adhesive, poly-(carbamate) adhesive of contact cement (cement) type for example Uniroyal " Silaprenes ", 3M " Scothgrip " adhesive, contact cement with isoprene.Other suitable adhesives comprise the combination of EVA adhesive film and PU adhesive film.For example, can and adhere to hermetically sealable film with two adhesive films together coextrusion.As selection, can be with hermetically sealable film and two together coextrusion of adhesive film.Then can use trilamellar membrane and hermetically sealable film is adhered to foam core.

In the present invention, during foaming process or at once afterwards, apply hermetically sealable film, so that foaming agent gas is retained in hermetically sealable film and a plurality of abscess.Because foaming agent gas can not be overflowed by hermetically sealable film, so the pressure in the composite foam product surpasses environmental pressure.Compare with the foam core that does not have hermetically sealable film, joint product shows improved resilience and compression performance.To exemplify below the preparation of describing joint product in the embodiment now.

First exemplifies embodiment

Exemplify in the embodiment first, use routine techniques for example to use injection moulding, convection furnace molding, microwave molding, radio frequency molding or any other foam moulded technology well known by persons skilled in the art to prepare foam core.After foam core forms at once, with hermetically sealable film adhere to outer surface with future self foaming agent gas be retained in the foam core.

Aspect preferred, foam core is by the mold apparatus preparation of using alternation radio frequency dielectric field with the die cavity heating.For example in one aspect, mobile mold apparatus can comprise top electrodes and bottom electrode and be arranged on therebetween mould.But expanded material and blowing agent are placed in the die cavity of mould and then during Heating Cyclic, compress.After heat stops, but the core that the expanded material of permission compression expands to meet the shape of mould and forms thus foaming when it cools off.The example of this class mold apparatus is disclosed in the U.S. Patent No. 4,441,876 of Marc, and among the open No.2006/0012082 of the United States Patent(USP) Nos. 4,524,037 of Marc and the United States Patent (USP) of Marc, these are incorporated herein by reference.According to the open No.2006/0012082 of the United States Patent (USP) of Marc, can form at the outer surface of foam core the epidermis of sclerosis.The epidermis of this sclerosis has reduced the speed of overflowing in the abscess of foaming agent gas from the closed-cell foam core, because this part of foam core still less sees through gas than the inside of foam core usually.

After forming foam core, then hermetically sealable film is adhered to the outside of foam core.Generally speaking, allow the foam core cooling so that the size and dimension of foam core is stable, obtain about environment temperature to about 100 ℃ temperature.Also the outer surface of preferred foams core remains under the substantially invariable temperature, so that hermetically sealable film carries out for being bonded under the usually identical speed of foam core.Importantly, after forming, foam core at once hermetically sealable film is put on foam core, so that the pressure in the foam core is higher than environmental pressure.Generally speaking, carry out in this 1-20 after foam core forms minute, but the degree that hermetically sealable film can postpone to adhere to depends on factor for example foam core thickness and density.

Most preferably, use is bonded in foam core for the equipment that applies alternation radio frequency dielectric field with hermetically sealable film.The equipment that exemplifies is shown among Fig. 2.More specifically, equipment 10 comprises top electrodes 12 and bottom electrode 14, and they all link to each other with electromagnetic energy source or the generator (not shown) that can work to produce dielectric field between electrode.Generator can comprise power tube and lc circuit, perhaps can selectively comprise solid state technology.Preferably, generator is transferred to frequency low-resonance in hope, this carries out when the total capacitance that comprises load (being foam core, hermetically sealable film and mould) equals total inductance.For example, top electrodes 12 can be high-voltage electrode, and bottom electrode 14 is earth electrode (or vice versa).Dielectric field can produce in the frequency of about 1MHz to 100MHz, and preferably produces at about 25MHz to 40MHz.Most preferably, dielectric field produces (they all allow centre frequency to be used for industry, science and medical science (ISM) application) at 27.12MHz or 40.68MHz.Also comprise mold 16 and bed die 18 in the equipment 10, they are defined in die cavity therebetween together.Cavity forming is to meet the shape of foam core.Mould is usually by silicon rubber V-1008 (being produced by Rhodia Inc.) preparation.

Generally speaking, hermetically sealable film 22 (with optional adhesive film) is preheated and then is placed on the bed die 18.Close die cavity and apply vacuum so that hermetically sealable film 22 (with optional adhesive film) is pre-formed as the shape of mould.Open die cavity, and the foam core 24 that then will form is placed between mold and bottom die and two electrodes.The foam core 24 that another hermetically sealable film 22 (and optional adhesive film) is placed between foam core and the mold 16 is pushed up.Generally speaking, too much hermetically sealable film (and/or optional adhesive film) extends beyond die cavity, and the outer surface that helps to guarantee foam core 24 covers fully, as always as shown in Fig. 2.Critical aspects is the whole outer surface that hermetically sealable film surrounds foam core 24.The alternation radio frequency dielectric field that produces between electrode heating hermetically sealable film 22, thus with the film hot adhesion in foam core 24.

The controlled heat that runs through foam core and/or hermetically sealable film (if necessary) can be always such as Marc, United States Patent(USP) Nos. 4,441, and such acquisition the described in 876, this patent is hereby incorporated by.Generally speaking, in order to obtain uniform heating, in all different-thickness zones of whole hermetically sealable film, keep constant electric capacity.This can equate with relative dielectric constant between the mould by making hermetically sealable film, preferably by finishing by the relative dielectric constant that changes mould with additive.As selection, by in the different-thickness area change top electrodes of hermetically sealable film and the spacing between the bottom electrode, electric capacity is equated.

To understand in most of situations the temperature that the melting/softening temperature of hermetically sealable film (with optional adhesive film) will begin to decompose less than the foam core that has formed.Therefore generally speaking, can not use any additive that hermetically sealable film is adhered to foam core.If yet hermetically sealable film and foam core made by similar material, therefore they may have similar dielectric constant and power factor, and similarly heat under the speed.Additive can be placed in the foaming mixture (with the foam core of gained), to change as required the rate of heat addition, described in the open No.2006/0012083 of the U.S. of Marc, the disclosure thing is hereby incorporated by as always.Required heating can depend on also whether described adhesive adheres to foam core with hermetically sealable film.Generally speaking, when using adhesive that hermetically sealable film is adhered to foam core, during heating steps, reach about 80-120 ℃ temperature.Yet when not using adhesive that hermetically sealable film is adhered to foam core, the temperature between the period of heating reaches about 150-190 ℃ usually.

After taking out from equipment 10, the composite foam product 20 that obtains is shown among Figure 1B.Excessive hermetically sealable film 22 can be removed from joint product, as always as shown in Figure 1A.Generally speaking, with the composite foam product die cutting to remove excessive film 22.Can use other to remove method, such as artificial cutting, tear etc.

In composite foam product 20, hermetically sealable film 22 surrounds the whole outer surface of foam core 24 and adheres to outer surface, and the gas of self foaming agent is retained in a plurality of abscesses of foam core in the future thus.Because foaming agent gas can not be overflowed by hermetically sealable film, so the pressure in the composite foam product 20 surpasses environmental pressure.Importantly between the outer surface of hermetically sealable film and foam core, there is not traps air, so that film contacts with intimate.Foam core contact with tight adhesion between the hermetically sealable film produce can not expected degree product integrality and can not be expectedly good impact absorption ability.

As an example, preparation comprises following foaming mixture as the foam core of resin compound, described foaming mixture has 35% ethylene-ethyl acetate, 39% ethylene-octene copolymer and 26% ethylene-propylene-diene rubber (" EPDM "), and ethylidene norbornene is as diene.Foaming mixture also comprises 2.6phr zinc oxide, 0.7phr stearic acid, 0.9phr polyethylene glycol, 8.8phr azodicarboamide, titanium, 1.0phr cumyl peroxide and 13phr fumed silica that 3.5phr is pure.Use known method to use RF to prepare foam core.After foam core forms about 0.5 hour, thermoplastic polyurethane film is adhered to the outer surface of foam core, thus the foaming agent gas in the foam core is retained under the pressure above environmental pressure.More specifically, use the mold apparatus with the general structure shown in Fig. 2.Use two kinds of adhesive film: Polyurethane 3281 (Bemis Associates, Inc., Shirley, MA) and EVA 449 (WorthenIndustries, Nashua, NH) that hermetically sealable film is adhered to foam core.It is thick that hermetically sealable film and adhesive film are about 0.5mm, and at first produce vacuum several seconds so that hermetically sealable film meets the shape of mould in bottom die.Foam core is put into mould, and on the top that hermetically sealable film and the adhesive film of another layer is placed on foam core.Then applied RF about 40 seconds at 27.12MHz.For relatively, prepare the foam core that does not wherein apply hermetically sealable film.

The result

Use ASTM D7121-05 to measure the resilience of froth pulp.Ball is fallen 23.5 inches, and measure resilience.The resilience of foam that does not have a hermetically sealable film was 55% in rear 1 day in formation, and after 1 year about 47%.The resilience of composite foam product of the present invention that hermetically sealable film arranged was 68% in rear 1 day in formation, and after 1 year about 62%.The density of foam core is about 8.5 pounds/cubic feet.

Also under 50 ℃ with foam compression to one half thickness after 6 hours, measure the compressibility of foam by measuring compression degree.The compressibility that does not have the eva foam of hermetically sealable film is 30%.The compressibility of the composite foam product of hermetically sealable film encirclement foam core is below 5%.

Second exemplifies embodiment

Exemplify in the embodiment second, as shown in Fig. 3 A and the 3B, the adhesion of the formation of foam core 124 and hermetically sealable film 122 (with optional adhesive film) is all carried out at the scene, and most preferably carries out in single consecutive steps as always.Generally speaking, use single mold apparatus to form foam core and hermetically sealable film is adhered to foam core.The hermetically sealable film that surrounds foaming mixture is provided in the die cavity of mold apparatus.When foaming mixture reaches its blowing temperature, but come the gas of self foaming agent so that expanded material expand into the shape with mold apparatus, the foam core of using the hermetically sealable film lining.Simultaneously, foam core and hermetically sealable film hot adhesion.

Comprise top electrodes and bottom electrode and be arranged on therebetween two moulds for the preparation of the preferred mold apparatus that flows of composite foam goods.Mould supporting barrier film is so that hermetically sealable film and foaming mixture (but comprising expanded material and blowing agent) can be placed between barrier film and the bed die.The mould that liquid is injected barrier film top to be making at first membrane deflects, and therefore basic all air discharged from mould.Then expanding so that liquid is extruded when foaming mixture during the Heating Cyclic, liquid is extracted out from mould.The example of this kind equipment is disclosed in the United States Patent(USP) Nos. 4,851,167 and 4,268,238 of Marc, and these patents are hereby incorporated by.The liquid that exemplifies comprises conducting liquid (such as mercury etc.) or dielectric fluid.

The equipment that exemplifies is shown among Fig. 3 A-3B.More specifically, equipment 110 comprises top electrodes 112 and bottom electrode 114, and they all link to each other with electromagnetic energy source or the generator (not shown) that can work to produce dielectric field between electrode.For example, top electrodes 112 can be high-voltage electrode, and bottom electrode 114 is earth electrode (or vice versa).Dielectric field can produce in the frequency of about 1MHz to 100MHz, and preferably produces at about 25MHz to 40MHz.Most preferably, dielectric field produces (they all allow centre frequency to be used for industry, science and medical science (ISM) application) at 27.12MHz or 40.68MHz.Also comprise mold 116 and bed die 118 in the equipment 110, they are defined in die cavity therebetween together.Mould is made by silicon rubber usually, its preferably with rigidity non--metal framework strengthens.Equipment also comprises the removable barrier film 130 that is arranged in the die cavity, its be used for foaming mixture 121 and hermetically sealable film 122 with can separate by the replaceable liquid 140 that move one or more gateways 142.

Generally speaking, as shown in Fig. 3 A, hermetically sealable film 122 (with optional adhesive film) is preheated and then is placed on the bed die 118.Close die cavity and apply vacuum so that hermetically sealable film 122 (with optional adhesive film) is pre-formed as the shape of mould.Open die cavity, but and the foaming mixture 121 that will comprise expanded material and blowing agent be placed between mold and bottom die and two electrodes, so that foaming mixture becomes the dielectric of capacitor effectively.Another hermetically sealable film 22 (and optional adhesive film) is placed on the foaming mixture 121 between foaming mixture 121 and the mold 116.Generally speaking, too much hermetically sealable film 122 (and/or optional adhesive film) extends beyond die cavity, and the outer surface that helps to guarantee joint product covers fully, as always as shown in Fig. 3 A.Form in case critical aspects is joint product, hermetically sealable film surrounds the whole outer surface of foam core 24.Another hermetically sealable film 122 is placed on the foaming mixture.Foaming mixture, film and mould become the dielectric of capacitor effectively.The alternation radio frequency dielectric field foamable mixture 121 that produces between electrode is so that the gas expansion that is formed by blowing agent and make foam core.Movably barrier film 130 upward deflects, so that it replaces replaceable liquid 140 by abscess 142 from die cavity.When foaming mixture 121 heating and expand and form foam core 124 (Fig. 3 B) when meeting hermetically sealable film 122, use alternation radio frequency dielectric field with film 122 hot adhesions in foam core 124.After pruning foam core outside excessive hermetically sealable film on every side, form thus composite foam product 20.

During foam core formed, the temperature of foaming mixture increased to about 150-200 ℃ usually, but the required definite temperature of preparation foam core depends on the component of specific foaming mixture.At Marc, U.S. Patent No. 4,441 described in 876, can run through foaming mixture and hermetically sealable film and obtain homogeneous heating as always, and this patent is hereby incorporated by.The temperature of hermetically sealable film reaches about 150-190 ℃ usually.Generally speaking, the softening temperature of hermetically sealable film is less than the blowing temperature of foaming mixture.

Understanding be the invention is not restricted to have by airtight membrane-enclosed single composite foam product of planting foam core material.That is, but foam core can comprise two or more different expanded materials with different foaming/molding temperatures and single heating or mold cycle (layering or mix).Can use Marc, disclosed equipment forms foam core among the open No.2006/0012083 of the U.S., and the disclosure thing is hereby incorporated by.

Composite foam product of the present invention can have any suitable size and dimension, depends on application and the purposes of hope.Generally speaking, composite foam product of the present invention can moulding with requiring high-efficient impacting to find application in absorbing, dress product (the especially heel in the footwear or sole shoe-pad, shoulder pad, leg pad, stern pad, the helmet), mat, seating systems, automotive interior packing material etc. such as motion.

As always as shown in Fig. 4 A and the 4B, can be always with respect to they advantages that should be used for describing the composite foam product as mat.Mat comprises large 12mx12m composite foam product 20, and this product has the hermetically sealable film 22 that surrounds foam core 24.The interior pressure of abscess that consists of foam core is higher than environmental pressure.Therefore, compare with traditional pad, described spacer has improved resilience and compression set properties.

The advantage of composite foam product can also be always with respect to they descriptions that should be used for as the heel cushion in the footwear.When using the traditional pin saddle, the downward pressure of heel causes the center of pad seriously to press down, so that the edge of heel cushion increases swollen making progress.When using air bag (bladder), gas moves forward and backward in capsule fast when being compressed power.This may be uncomfortable for the wearer.When use comprised by the heel cushion of airtight membrane-enclosed foam core, the center of pad minimally pressed down and also exists increasing of minimum swollen around the edge of pad.Significantly resilience and stand less compression of heel cushion.Generally speaking, when being compressed power, the abscess of gas in foam core in the composite foam product of the present invention advanced relatively lentamente to abscess.

To find out that from aforementioned content the present invention is very suitable for realizing all targets and purpose mentioned above, together with other apparent and intrinsic advantages of the present invention.Because under conditions without departing from the scope of the present invention, can make many possible embodiments of the present invention, therefore will understand all things described herein or illustrated in the accompanying drawings will be interpreted as illustrative, and hard-core implication.Although illustrated and discussed concrete embodiment, certainly can carry out various improvement, and the invention is not restricted to the layout of concrete form as herein described or part and step, except these restrictions are included in the scope of following claim.In addition, close and be useful and can be not do not close and use with reference to other features and subgroup understanding some features and subgroup.This scope by claim is conceived and is in the scope of claim.

Claims

1. method that forms the composite foam product comprises:

But form foam core by expanded material and blowing agent, a plurality of abscesses are arranged in the described foam core, described a plurality of abscesses will be retained in wherein being higher than under the pressure of environmental pressure from the gas of described blowing agent, and described foam core has outer surface; With

Hermetically sealable film is adhered to the described outer surface of described foam core;

Wherein said adhering step and described formation step are carried out simultaneously or are at once carried out after forming step, being retained in the described abscess under being higher than the described pressure of described environmental pressure from the described gas of described blowing agent.

2. the process of claim 1 wherein that but described expanded material is selected from polyvinyl resin, acrylic resin, thermoplastic resin, or their mixture.

3. the method for claim 1, but wherein said expanded material is selected from the polyolefin of high density polyethylene (HDPE), low density polyethylene (LDPE), LLDPE, vinyl-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-acrylate-maleic anhydride terpolymer, ethylene-methyl methacrylate glycidyl ester copolymer, ethylene-methyl methacrylate ethylene oxidic ester-methacrylate terpolymer, ethylene-methyl methacrylate ethylene oxidic ester-vinyl acetate terpolymers, ethylene-alpha-olefin copolymer, modification, and haloflex.

4. the process of claim 1 wherein that but described expanded material is selected from Noblen, propylene-ethylene random copolymer, propylene-ethylene block copolymer, propene-1-butene random copolymer, and propylene-ethylene-butene terpolymer.

5. the method for claim 1, but wherein said expanded material is selected from polyvinyl chloride, polyvinyl chloride-acetate copolymer, chliorinated polyvinyl chloride, polyvinyl chloride-vinyl-vinyl acetate copolymer, polyvinyl chloride-urethane copolymers, acrylonitrile-butadiene-styrene copolymer, MBS, SBS, acrylonitritrile-styrene resin, PVC-nitrile rubber, and other vinyl-based toners.

6. the process of claim 1 wherein that described blowing agent is selected from N-nitroso compound, sulfohydrazide, sulfonyl semicarbazides, ammonium and azo compound.

7. the process of claim 1 wherein that the described gas from described blowing agent is inert gas substantially.

8. the process of claim 1 wherein that described hermetically sealable film is selected from one or more in polyolefin, polyurethane, polyvinyl compound, polyethers and the polyester.

9. the process of claim 1 wherein that described hermetically sealable film is selected from polyethylene/vinyl alcohol copolymer, poly-(vinylidene chloride) copolymer, PETG, polyamide, nylon and thermoplastic polyurethane.

10. the process of claim 1 wherein that described adhering step undertaken by adhesive film being put between described foam core and the described hermetically sealable film.

11. the process of claim 1 wherein that the step of the described foam core of described formation may further comprise the steps:

But described expanded material and described blowing agent are inserted mould;

But cross over described mould and apply alternation radio frequency dielectric field to heat described expanded material.

12. the method for claim 10, wherein said alternation radio frequency dielectric field produces between the first top electrodes and the second bottom electrode.

13. the method for claim 12, wherein said the first top electrodes are to have 1000-10, the high-voltage electrode of 000V voltage.

14. the method for claim 1:

The step of the described foam core of wherein said formation may further comprise the steps: but described expanded material and described blowing agent are inserted mould, but and cross over described mould and apply alternation radio frequency dielectric field to heat described expanded material and to form described foam core; With

Wherein said adhering step may further comprise the steps: the described outer surface that surrounds described foam core with hermetically sealable film, the foam core of described encirclement is inserted mould, and cross over described mould and apply alternation radio frequency dielectric field with the heating hermetically sealable film and described film is adhered to the described outer surface of described foam core.

15. a method that forms the composite foam product comprises:

But formation comprises the foaming mixture of expanded material and blowing agent;

Surround described foaming mixture with hermetically sealable film;

Heat described foaming mixture and described hermetically sealable film, wherein said foaming mixture forms has the foam core of outer surface, a plurality of abscesses are arranged in the described foam core, have in described a plurality of abscesses at the gas from described blowing agent that is higher than under the pressure of environmental pressure; And wherein described hermetically sealable film is adhered to the described outer surface of described foam core.

16. the method for claim 15, wherein said heating put on described foaming mixture by the alternation radio frequency dielectric field that will have frequency and carry out.

17. the method for claim 16, the described frequency of wherein said alternation radio frequency dielectric field is about 1MHz to 100MHz, and the described voltage of wherein said alternation radio frequency dielectric field is about 1000-10,000V.

18. the method for claim 15 may further comprise the steps:

Described hermetically sealable film is arranged on the bottom die of die cavity of the mold apparatus that flows, described mobile mold apparatus has mold and described bottom die;

Described foaming mixture is placed on the described hermetically sealable film in the described die cavity;

Other hermetically sealable film is placed on the described foaming mixture in the described die cavity, so that described hermetically sealable film surrounds described foaming mixture; With

Heat described foaming mixture and form described foam core.

19. the method for claim 18, wherein said mobile mold apparatus further comprises movably barrier film, described barrier film with described foaming mixture and described hermetically sealable film with can separate by the replaceable liquid that move one or more gateways; With

Wherein said heating is moved described removable barrier film and is replaced described liquid by described one or more gateways.

20. a composite foam product comprises:

Have a plurality of foam core that are the abscess of hole-closing structure, described foam core has outer surface, and

Tight adhesion is in the hermetically sealable film of the whole outer surface of foam core;

Wherein foaming agent gas is retained in described a plurality of abscess under surpassing the pressure of environmental pressure by described hermetically sealable film.

21. the composite foam product of claim 20, the described pressure in wherein said a plurality of abscesses are about 1.1-2.0 times of environmental pressure.

22. the composite foam product of claim 20, it is comprised of following substantially: have a plurality of foam core that are the abscess of hole-closing structure; With tight adhesion in the whole outer surface of foam core so that be retained in hermetically sealable film in a plurality of abscesses at the pressure lower frothing agent gas that surpasses environmental pressure.

23. the composite foam product of claim 20, it is comprised of following: have a plurality of foam core that are the abscess of hole-closing structure; With tight adhesion in the whole outer surface of foam core so that be retained in hermetically sealable film in described a plurality of abscess at the pressure lower frothing agent gas that surpasses environmental pressure.

24. the composite foam product of claim 20, wherein said foam core are by polyvinyl resin, acrylic resin, thermoplastic resin, or their mixture consists of.

25. the composite foam product of claim 20, wherein said hermetically sealable film is selected from one or more in polyolefin, polyurethane, polyvinyl compound, polyethers and the polyester.

26. the composite foam product of claim 20, wherein said foaming agent gas comprise that one or more are selected from the gas of nitrogen, carbon dioxide and carbon monoxide.